Towed vehicle electric brake control

Abstract

An electronic brake control for trailers utilizing solenoid operated electric brakes wherein trailer braking is controlled by sensing the rate of deceleration of the towing and towed vehicle producing an electric signal controlling a voltage controlled oscillator having a fixed frequency output and a variable pulse width, the pulse width increasing proportional to the rate of deceleration. The pulse signals are amplified and energize the towed vehicle electric brakes in an oscillating or pulsed manner to minimize skidding and brake locking. A light sensing circuit selectively shielded by a pendulum produces the automatic deceleration responsive signal, and manual apparatus are employed to produce trailer braking without braking of the towing vehicle. Additionally, the automatic electric brake system control through the brake light circuit is by-passed and isolated by actuation of the emergency warning brake light system.

We claim: 
     
       1. An inertial sensor for braking control apparatus as in towed vehicles comprising a shaft, a housing adjustably supporting said shaft on an axis transverse to the direction of movement of said towed vehicle, a laminated thin cantilevered spring member affixed at its upper end to said shaft and being weighted at its lower end and said spring member carrying a light interrupting shield, a light source provided on one side of said housing, and a light sensing target on the other side of said housing, said source and said target being on a common axis interrupted by selected movement of said spring member. 
     
     
       2. In the structure of claim 1 wherein said laminated thin spring member is metal and intermediate the layers of said laminar is a nonbrittle resin material bonded on both sides to said metal. 
     
     
       3. In the combination of claim 2 wherein said metal in said laminate is thin strips of beryllium copper.